PlatformSpecificIsNan() function pointer interface for IAR

Compiles OK with gcc. Anyone to test this(@hraftery possibly)?
Fix indentation
PlatformSpecificIsNan() function pointer interface for armcc

Fixed indentation
Compiles OK with gcc. Anyone to test this(@bortsov possibly)?
PlatformSpecificIsNan() function pointer interface for Symbian

Cannot be compiled without appropriate compiler. Anyone to
compile and test this (@basvodde)?
PlatformSpecificIsNan() function pointer interface for Visual Studio

Compiled and tested with VS2008
Merge pull request #371 from arstrube/fp_iar

Add PlatformSpecificIsNan() function pointer interface for IAR
Merge pull request #373 from arstrube/fp_armcc

PlatformSpecificIsNan() function pointer interface for armcc
Merge pull request #375 from arstrube/fp_msvc

PlatformSpecificIsNan() function pointer interface for Visual Studio
Merge pull request #374 from arstrube/fp_symbian

Add PlatformSpecificIsNan() function pointer interface for Symbian